First time in the water = fail!

[Gas Giant]

Engine is a '63 Evinrude Big Twin 40hp, Model No. 43053. It has a '61 carb, fuel pump, and lower unit on it. Carb freshly rebuilt, ignition is new, and I just replaced the flywheel key because it was sheared when I got the motor. Had a tank of fresh 24:1 fuel too.

Okay, had the engine running good, so I decided to take the boat for a spin today. It was my first time in this boat, which is a little 14 foot Orlando Clipper. I warmed it up in a barrel before leaving the house, the engine gave no indication that it was unhappy.

Put it in the water at the boat ramp, and it was cranky - it didn't want to run for long. But I managed to get it going, and after a minute or two it was doing fine. Pulled away and gave it some gas, and it would rev up and speed the boat up, but then the engine would bog back down a few seconds later. If I slowly opened the throttle, it didn't bog down, and let me tell you, that little boat will straight out FLY with that 40 on it.

However, coming back to the boat ramp, I had to slow back down to idle in the manatee zone, and when I came back down off a plane, it sputtered and died. Wouldn't restart no matter what I did. No sputtering or anything, just cranking and cranking with no fire. I decided to save the battery for the electric trolling motor to get me home (I brought it for this exact reason ).

Well, after getting it home, it sat for a few hours while I recharged the battery. Went to start it, and it backfired out of the carb. My automotive experience tells me this is a timing issue, but not sure what it means with an outboard. I cranked it again, and it fired up, but it was idling fast. Couldn't find a reason why.

Shut it down, and started it again, and it was running, but backfiring out of the exhaust badly. I shut it off after a few seconds and stopped messing with it at this point.

So, I'm going to test compression again tomorrow to make sure something didn't go horribly wrong. (it was 100psi on each cylinder a week ago). But I am looking for ideas on what it could be. Could I have sheared a flywheel key again? I used an Evinrude flywheel key and torqued the flywheel nut to 105 ft-lbs when I replaced it last Friday.

Any ideas are appreciated. Not quite sure where to begin diagnosing, and driving that little water rocket is quite addicting.

 

[James R]

Re: First time in the water = fail!

I would question the 24:1 mix. I have had '62 motors and always run them on 50:1.
Sounds like the plugs are oiling up.

 

[JDusza]

Re: First time in the water = fail!

What do you think about fuel? Sounds like it isn't getting enough fuel, reliably.
How was the carb rebuild? Any air leaks in hoses or gaskets in delivery system?
J

 

[1946Zephyr]

Re: First time in the water = fail!

The '63 motors are supposed to be run on 24:1. His issue here is likely to be either the ignition, or dirt in the carburetor and possibly a weak fuel pump. Hey Gas Giant, is this the motor you just bought?

 

[kfa4303]

Re: First time in the water = fail!

I agree. 24:1 is best. I run it in my '66 33 hp and 20 hp motors without issue. I'm thinking it's a fuel delivery issue too. I would double check the carb passages, make sure the float needle is properly seated and make sure you're getting good strong spark on both cylinders. The lack of fire suggests something may be wrong with the ignition. You can check to see if the fuel pump is working by manually pumping the primer bulb with the motor off. It should get and stay firm for several minutes. If it doesn't, then you may have a bad fuel pump. Don't worry there are always a few gremlins to work out on the first few trips. These links may help.

http://www.duckworksmagazine.com/04/s/columns/max/24/index.cfm

http://forums.iboats.com/showthread.php?t=167352

 

[Gas Giant]

Re: First time in the water = fail!

Thanks for the replies.

Yeah, this is the motor I just got.

The primer bulb does get firm, but I have never checked how long it stays firm.

I'll pull the carburetor off again today. When I rebuilt it, I tore it down to a bare shell, even yanked out the welch plugs, and soaked it in a bucket of carb cleaner overnight. Then I took it out and blew out all the passages with aerosol carb cleaner and compressed air. And then reassembled it with a new carb kit. But, obviously something is wrong, so I'll pull it back apart.

Other than the diaphragm, and the spring, there isn't much more to that fuel pump, is there? I'll put my other fuel pump on and see if that helps.

But, would a fuel problem be causing my current issue, which is the wicked backfires?

Anyway, I'll report back with what I find today.

 

[Bob_VT]

Re: First time in the water = fail!

Great motors!!

If the gremlin is still persistent........ I would suggest pulling the flywheel and re-checking the ignition. Now that you had a short run ......it is not out of the realm of reason but something could have moved with the points, maybe too much oil /grease got on the points and the other culprit is to recheck all the wiring and wire routing under the flywheel.

I spent MANY MANY Summer's pull starting the old 33's an 40's

 

[lindy46]

Re: First time in the water = fail!

But, would a fuel problem be causing my current issue, which is the wicked backfires?

Anyway, I'll report back with what I find today.

I'd recheck that flywheel key.

 

[HighTrim]

Re: First time in the water = fail!

Check the flywheel key.

Check that the low speed needle did not vibrate loose and move on you.

 

[1946Zephyr]

Re: First time in the water = fail!

Yep, that wicked backfiring is probably a lean sneeze. This is usually caused by the low speed needle not being rich enough. Set it at 1 1/2 turns out. Or you may have one cylinder not firing good. As suggested, take a look under the flywheel.

 

[Gas Giant]

Re: First time in the water = fail!

You guys are clever!

The slow speed needle had vibrated loose. I tightened the packing nut a bit and ran it out 1 1/2 turns after lightly seating it. For the heck of it, I started it up, but it's still sneezing like it inhaled a bunch of pepper. In fact it shut itself off doing that.

So, when I have a helper available, I am going to have to pull the flywheel. Hopefully tomorrow.

Anyway, the silver lining is that I still have good compression on both cylinders. So that's good!

I'll report back with that I find.

 

[glenner]

Re: First time in the water = fail!

24 to 1...? go 50:1 and use mid octane gas

 

[HighTrim]

Re: First time in the water = fail!

24 to 1...? go 50:1 and use mid octane gas[/QUOTE

I am going to STRONGLY disagree with this. No offense Glenner. It is exactly that which has ruined many a good motor.

 

[Gas Giant]

Re: First time in the water = fail!

I'm going to keep it safe and use 24:1, Evinrude's website even says to for engines '63 and older. I'd rather have too much oil than not enough.

 

[nwcove]

Re: First time in the water = fail!

I'm going to keep it safe and use 24:1, Evinrude's website even says to for engines '63 and older. I'd rather have too much oil than not enough.

plugs are cheaper than powerheads!

 

[gus-gus]

Re: First time in the water = fail!

I am wondering who could make an engine backfire with a fuel/oil mix change? I mean come on people! The fuel mix is for lubrication, not changes which end the fire comes out of.

This has about zero percent chance of it being fuel/oil. It has 100% chance of being electrical/timing. I think timing is the issue and I would be willing to bet the key way is missing on the flywheel. If it was sheared, which is almost unheard of in a good motor, then there is an issue with the crank, the shear set up or the flywheel itself.

As far as mix goes. If the oil says 50 to 1 or less (100 to 1) on the container then 50 to 1 will work on all 2 stroke engines. Old or new, they use the exact same principal and neither will be harmed with a 50 to 1 usage. I burn 50 to 1 in everything, weed wackers, Dirtbikes, chainsaws, pressure washers, snowmobiles, even in all my old Evinrudes and Mercs. You can run it down to 24 to 1 if you want, but the diff is more smoke, more plugs, more trouble (using more than twice the oil) and poorer fuel economy, worsening the oil consumption.
Note: I have never burned, broken or smoked a 2 stroke in 50 years of using them, NEVER. I have been exclusive 50 to 1 since 1983. Even on a few darned old Elgin outboards and Sears Outboards.

Your trouble is easiest found by thinking, heat/ignition = fuel/propellant = air/compression. Remove any one and it wont run, but remove each one, one at a time and each provides a completely different feedback.

Good luck.

 

[rolmops]

Re: First time in the water = fail!

The '63 motors are supposed to be run on 24:1. His issue here is likely to be either the ignition, or dirt in the carburetor and possibly a weak fuel pump. Hey Gas Giant, is this the motor you just bought?

Actually,OMC came out with a bulletin in 1964 stating that all OMC outboards down to 1961 can be run on a 1:50 mix.This bulletin ignored the fact that 5 hp and less engine still had bushing bearings.

 

[tx1961whaler]

Re: First time in the water = fail!

I am wondering who could make an engine backfire with a fuel/oil mix change? I mean come on people! The fuel mix is for lubrication, not changes which end the fire comes out of.

This has about zero percent chance of it being fuel/oil. It has 100% chance of being electrical/timing. I think timing is the issue and I would be willing to bet the key way is missing on the flywheel. If it was sheared, which is almost unheard of in a good motor, then there is an issue with the crank, the shear set up or the flywheel itself.

As far as mix goes. If the oil says 50 to 1 or less (100 to 1) on the container then 50 to 1 will work on all 2 stroke engines. Old or new, they use the exact same principal and neither will be harmed with a 50 to 1 usage. I burn 50 to 1 in everything, weed wackers, Dirtbikes, chainsaws, pressure washers, snowmobiles, even in all my old Evinrudes and Mercs. You can run it down to 24 to 1 if you want, but the diff is more smoke, more plugs, more trouble (using more than twice the oil) and poorer fuel economy, worsening the oil consumption.
Note: I have never burned, broken or smoked a 2 stroke in 50 years of using them, NEVER. I have been exclusive 50 to 1 since 1983. Even on a few darned old Elgin outboards and Sears Outboards.

Your trouble is easiest found by thinking, heat/ignition = fuel/propellant = air/compression. Remove any one and it wont run, but remove each one, one at a time and each provides a completely different feedback.

Good luck.

Don't confuse the gasil ratio "lean" with the fuel:air ratio "lean". A lean fuel:air ratio will certainly cause a backfire on that twin. Also, the advice for "50:1 for all 2 strokes" is BS. If your idea of an old engine is 1983, then you would be correct, but the early/pre-1960's twins may not have a complete set of roller bearings and will suffer greatly at 50:1. Try running a 1960 3 hp on 50:1 and see how long it lasts.....

 

[HighTrim]

Re: First time in the water = fail!

Don't confuse the gasil ratio "lean" with the fuel:air ratio "lean". A lean fuel:air ratio will certainly cause a backfire on that twin. Also, the advice for "50:1 for all 2 strokes" is BS. If your idea of an old engine is 1983, then you would be correct, but the early/pre-1960's twins may not have a complete set of roller bearings and will suffer greatly at 50:1. Try running a 1960 3 hp on 50:1 and see how long it lasts.....

I had typed up a lenghty response similar to yours, then deleted it. Some people just dont learn until they rebuild powerheads improperly run on 50-1 or even worse 100-1!

EDIT: typed up more but we'll leave it at that,

 

[freddyray21]

Re: First time in the water = fail!

24:1 like others have said 50:1 on the old motors burnt a lot of them up. check to see if you have spark on both cylinders. then check fuel. adjust out the needles to get rid of the lean sneeze. one and a half out on the low speed it just to get it to run. It will need to be adjusted.